Fertilizer



Patented Dec. 9, 1924.

UNITED STATES PATENT OFFICE.

ALFRED H. COWLES, OF SEWAREN, NEW JERSEY, ASSIGNOR TO THE ELECTRICSMELT- ING AND ALUMINUM 00., OF CLEVELAND, OHIO, A. GORPORATIOLI OFOHIO.

FERTILIZER.

No Drawing. Original application filed December 28, 1918, Serial No.268,674. Divided and this application tiled July 12, 1923. Serial No.651,176.

To all whom it may concern:

Be it known that I, ALFRED H. Cownns, a citizen of the United States ofAmerica, residing at Sewaren, in the county of Middlesex and State ofNew Jersey, have invented certain new and useful Improvements inFertilizers, of which the following is a,- full,

clear, and exact description.

My invention relates to fertilizers, and 1s a division of my applicationSerial No. 268,674, filed December 28, 1918.

' At the present time, soils from the decomposition of plants andmanures are known to contain hydrated silica, also art1fic1al mixturesof fertilizers, in many instances, contain it in indefinite amounts asan accidental impurity. Liebig, as early as 18fl0, from hisinvestigations of the composit on of the ashes of various plants,thought silica necessary as a. plant food. Thisresulted 1n experimentswith potassium and sodium s1l1- cates to supply silicato augment thegrowth of grasses, cereals and plants containing ver large percentagesof silica in their ske etons.

Knop and other plant physiologists, succeeded in growing plants withsilica supposed to be absent as a nutriment, and afterwards, when theLaw of the minimum" was proven and accepted, silica in any form waseliminated by agricultural chemists as an essential elementto use inartificial mineral fertilizers. (Soil Conditions and Plant Growth by E.J. Russell, 1915 edition, pp. 30,46,112.)

It is now universally assumed that silica, clay, zeolites and feldsparsin soils, furnish a superabundarce of silica and therefore its additionas a fertilizer is unnecessary. These substances and natural silicatesare so minutely soluble that the assumption is unwarranted. By annualrepeated growths of ve tation upon uncultivated land, hydrate doublesilicates, while slowly degradin to clay, furnish to soil waters solublesihca. This accumulates and is held by zeolites, vegetation and humus,and in time, an abundance of the same is in such soils and furnishesnormal amounts to successive rowths. Cultivation with exhaustion of umusand annual removal of crops, ex-

hansts the soil faster than it is replenished. Figuratively, the spongehas been removed facilitating sub-soil drainage.

that has accumulated and retained in suflicient amount this materialwhich forms a large part of the natural skeletons of plants. Cultivationalso accelerates this loss through Thus it is that soil water solutionsin soils on cultivated lands largely free from humus, have becomedeficient in the quantity of soluble silica that is needed for maximumplant growth; therefore:

My invention consists in designingly using variable proportions ofhydrated silica containing more than fifteen (15) per cent of water ofhydration obtained from calcium silicates containing ratios ranging from2 /21 to a little less than one to 1, for example, 0.70:1, calcium oxideto silica, to supply deficiencies of soluble silica required for plantgrowth. Such silica containing various amounts of water is securable bythe action of carbonic and other acids and moisture upon various simpleand complex silicates, artificial or natural.

It further consists in the intentional addition or formation of designedproportions of such silicates in the preparation of fertilizer mixturesor substances, either by addition of such hydrated silica or suchsilicates and an acid, with the intentional design of increasin orsupplying intended amounts of hydra silica to such mixtures. Myinvention or discovery further embodies adding to soils, simple orcomplex, calcium silicates artificially prepared, characterized in thatcarbonic acid of the soil waters will decompose said com ounds ormixtures with. a liberation of hy rated silica of a more. soluble typethan those hydrated silicas that ordinarily occur in nature as minerals.The presence of other essential fertilizers such as potash, iron oxide,phosphoric acid and soda as impurities in said complex silicates, is notto be avoided when there is a. proper allowance of calcium oxide tosilica in the mixture, so that upon the action of carbonic acid andmoisture, there shall be formed a large amount of hydrated silica bytheir decomposition when used,

In my invention any silicate may be used in any manner so as to suppl tothe soil or fertilizer mixtures, designe amounts of available addedsoluble silica. There are certain silicates and mixtures of silicates torender available the potash therein for fertilizer purposes. In suchattempts, it was thought necessary to use potash minerals of high potashcontent and only sufficient lime to displace the molecular weightproportions of potassa that were. in the constitution of the potashsilicates therein. It is now thought that such processes are valueless.In these attempts, the product 'secured'from, for instance, potashfeldspar and lime, the design was to lock the lime in the form of aninsoluble mono-calciumaluminum-silicate, freeing the potassa (K 0) forsolution. It was not realized that impure feldspars and other potashmineral silicates mixed with free silica, can be treated preferably atjust their sintering temperature after mixing with two or up to two andone-half molecular weight proportions of lime to each single molecularweight proportion of silica in the mixture, and that after suchtreatment, the action of carbonic acid and moisture on the product, willcause the alkali 'aluminate necessarily formed to decompose withliberation of potassium carbonate, and also will decompose all excess ofdi-calciumsilicate, .with the liberation of soluble calcium bicarbonateand hydrated silica. The residue left after long soil leaching, will,for example, be a calcium potassium zeolite containing in itsconstitution a "ariable fraction of a molecule of calcium oxide and avariable fraction of a molecule of potassium oxide (ammonium and otheralkali metal oxides may form a art of this fraction) one molecule ofalunnna and ultimately two molecules of silica together with water ofchemical combination, the quantity of which inversely varies to a markeddegree with temperatures to which soil waters are naturally subjected.These substances are the hydrated feldspars or zeolites of nature. Theyare permutites, and when immersed in a mixed solution, like soil waters,they reciprocally exchange, especially alkali earth metal oxides andalkali metal oxides, inclusive of ammonia. These exchanges are governedby the laws of mass action as bearing upon the action of various ions,with variations of temperatures and variations of the density ofdifierent solutes. Zeolites are recognized as valuable soilcens'tituents.

Further, as a part of my invention, is

' siumaluminate.

the process of manufacturing the product described which consists intreating in suitable furnaces, potash bearing silicious rocks, such asgranites, schist's, 'glauconite marls and others, or mixtures thereof,all

containing large amounts of free silica, with. two and a tractionmolecular weight prooxide present in the mixture is beneficial bothbecause of its fertilizer value and because by its use 'a lowertemperature Suiiices for complete sintering or fusion.

The reasons, though not vital, for this excess of lime over the 2 to 1ratio of lime to silica are: First to supply one molecular weightproportion of lime to each molecular weight proportion of alumina in themixture, thus preventing a small amount of silica from becominginsoluble through its forming) with alumina kaolinite A1 0 2SiO,XH,Second, under con itions of imperfect mixing, an excess insures enoughlime present in all parts of the charge so that at least two molecularweight proportions of calcium oxide can combine with one molecularweight proportion of silica (SiO,), thus enabling all the potassa toassume a soluble form as mono-potas- An excess of lime to silica overthe 2 1 ratio leads to higher melting point mixture and possiblevolatilization of the potassa.

In the foregoing, I have mentioned the use, in a mixture designed tosinter, of two molecular weight proportions of lime or calcium carbonateto each single molecular weight proportion of silica. In this case,after treatment with CO2, such alumina as may be present in the mixtureis left free rive 1 as hydrated alumina and it naturally enters intocombination with hydrated silica to from hydrated alumina silicates (Al-0,, 2S1O H O) or the insoluble clay substances of soils. 'In doing this,however,

lime adheres naturally to the compound and some alkali metal oxide,therefore, if a slight'excess of lime over and above the two moleculesof CaO to one 810 be employed in the mixture, and if the mixture be wellsintered the alkali metal oxides will be freed during leaching withgreater facility, and it may be supplied in excess even to the extent ofan added molecular weight pro ortion of lime to each single molecularweight proportion of alumina in the total mixture. The tri-calciumsilicate is too refractory for good economical working.

(As bearing upon the chemistry of form'- ing a proper mixture forsintering, see my pending application, Serial No. 62,486, filed ovember20th, 1915.)

My invention can also be carried out by employing sintered or fusedmixtures of lime and silica or compounds of lime and silica preferablylower in their ratio of lime to silica than two and one-half molecularweight proportions of lime to one of silica. In forming these mixturesor compounds, magnesium carbonate, iron oxide and potash as impuritiesin the limestone or silica are advantageous. Such mixtures can be formedin a rotary or other suitable furnace and by well known means,distintegrated to powders or mineral wool. So formed, it always containsa little alkali, iron oxide and alumina as impurities. Vhen calciumsilicates are used, it is desirable to have them as low in lime contentand high in silica content as is consistent with economical fusion orsintering and decomposition when finely divided, by the action ofcarbonic acid and moisture. Economical methods of roducing them are wellknown. Tri-calcmm silicate sinters at too high a temperature andfurnishes less hydrated silica, therefore, I would not recommend itsuse, though it will decompose by the action of carbonic acid andmoisture and furnish soluble silica to the soil. The mixture of lime andsilica that melts at the lowest temperature, contains a little less thanone molecular weight proportion of calcium oxide to one of silica; .70of molecule of lime to one of silica works well. With too low an amountof lime in the mixture, it ceases to be acted upon by carbonic acid andmoisture,.and the use of such should be avoided.

Hydrated calcium silicates can be produced by treating infusorial earth,best when high in water of chemical combination, with slacked lime atordinary temperatures. Infusorial earth may contain as high as thirteenper cent of water. This reaction does not take place with groundcrystalline silica, thus native hydrated silica may, by treating withslacked lime and water, produce calcium silicates suitable for use.

If the described more soluble types of hydrated silica, or theutilizable calcium silicates, be added to a soil'devoid of any one ofthe other essential mineral fertilizer salts, no valuable resultsv wouldbe expected. In most soils these other essential salts occur in greateror smaller amounts. \Vhen calcium silicate is added, there is formedcalcium bicarbonate in the waters of the soil. It is known that calciumbicarbonate acting on hydrated silicates containing potassium oxide andalumina, will liberatepotassium oxide to form bicarbonate of potassium,and, therefore, the lime performs a double function of supplying lime tothe soil waters and also soluble potassium salts. While the fore goingis known, one must conclude that the acid properties of silicic acid.tend to release phosphoric acid from its insoluble combination in thesoil, thus also performing a double function. For growth of plants,deficiencies in all essential mineral fertilizers below that which isrequired for their full growths should be supplied to their soil watersin soluble form.

I have made comparative plant rowth experiments using chemicallyequivalent calcium oxide (CaO) proportions in calcium silicate, calciumcarbonate, calcium hydrate, calcium carbonate plus hydrated silica mixedtherewith, and calcium hydrate plus hydrated silica in mixture, in soilsboth completely and partially devoid of lime, and found that in thosecases where I was supplying hydrated silica to the soil, even as low asone quarter of a ton to the acre, such supply has greatly augmented thegrowth and luxuriance of nearly all the many plants submitted tocompetitive tests. These experiments have been performed both in potsand on plots of land, and with each plant, repeated comparativeexperiments have been made, and in manycases repeated several times. Theaggregate result of this work has proven that silica in soluble form isneeded to make up that deficiency that exists in all soils that havebeen submitted to long cultivation.

I find this also true when I supply lime, silica and potash secured bytaking a low grade potash feldspar, potash micas or mixtures of the likewith silica, that has been sintered with lime to furnish the two plusmolecular weight proportions of lime to each single molecular weightproportion of silica in the mixture. Experiments with such a sinter, Ihave carried on parallel with those that have been mentioned above, andthe same show, in many cases, an improvement over using the properproportioned amount of calcium silicate or lime plus silica. I,therefore, have discovered that low grade maximum Illll potashcontaining rocks can, if properly sintered or melted with lime (orlimestone) be made to give up to the soil waters, hy-

drated sllica with potassa K 0 and most of the lime employed, whilst apart of the lime will remain to form a calcium zeolite (or the like)with a relatively lower amount of contained silica than is in any of thepure double silicate minerals of said rocks from which such zeolite orpermutite materials will slowly form, by action of carbonic acid rocksand mineral mixtures. Deficient soils may be improved as to theirhydrated silica content by subjecting calcium silicates con- .tainingvariable amounts of alkali metal oxide and alumina, the silicates havinga ratio of lime to silica of two and a fraction lime to one of silica,to the action of carbonic acid and water in said soils.

Proper fineness of the materials I have mentioned when applied to thesoil, can be easily appreciated by all those skilled in the art, andsuch fineness of division was carefully observed in using the mixturesmentioned in the competitive plant growth experiments already described.A fineness oi 80 mesh is favorable'to good results.

I disclaim the use of soluble alkali metal silicates for application tothe soil or to add to fertilizer mixtures as a source of supply ofsoluble silica. Plant growth experiments, long ago abandoned, made withthem, have led plant physiologists into the error of considering thesoluble types of silica as nonessential in the fertilization of plants.These old experiments failed for a chemical reason that has not beenrecognized in this formed of lime, alkali metal oxide and silica.

When these old experiments were made, as

- there was always employed an excess of lime,

or lime salt, above that necessary to form this insoluble product, suchinsoluble salts formed. Therefore, when the experimenters thought theywere furnishing soluble silica to the soil water, this silica was beingim mediately precipitated out and so rendered non-available to theirplants. The deductions drawn from their experiments were, therefore,misleading. These deductions have found their way into the literature ofthis art. Locking up of the silica occurs even with clay present, orwith zeolites in the soil, when soluble alkali silicates are used. Thesilica enters into combination to replace silica that has formerly beenleached away from zeolites during their slow process of de radation toclay. From these causes, the o d comparative plant growth experimentsfailed to show the value of silica hydrates. This should have beenrecognized from the art relating to the manufacture oi artificial stonefrom alkali silicates or water glass and said lime compounds. Also fromthe Work performed by Daubree, T. Sterr Hunt and others on the reactionof alkai silicates in the artificial formation of insoluble minerals. Idisclaim the use of natural mono-calcium silicates, such as{Vollastonite, and corresponding mono-magnesium silicates, such asEnstatite, since they are too rare in nature to form the basis of anycommercial process and have only been the sub ect of scientificexperiments.

In my application Serial No. 192,028, filed September 18, 1917, of whichthis application is a division in part, claims are made broadly to thefeature of adding soluble calcium compounds described herein tofertilizer compositions.

\Vhat I claim is 1. A fertilizer composed of artificially preparedcalcium silicate other than nono-calcium silicate wherein the ratio ofcalcium oxide to silica varies between a little less than the ratiorequired to form di-calcium silicate and, a little less than the one toone ratio to form mono-calcium silicate.

2. A fertilizer comprising an artificial calcium silicate other thanmono-calcium silicate wherein the ratio of calcium metal oxide to silicais less than the molecular ratio that exists in di-calcium silicate.

3. A fertilizer comprising an artificial calcium silicate wherein theratio of calcium metal oxide to silica is less than the molecular ratiothat exists in di-calcium silicate, and containing impurities such aszeolite material and iron oxide.

4. Fertilizer materials in pulverulent form comprising artificialcalcium silicate other than mono-calcium silicate wherein the ratio ofcalcium oxide to silica varies to form dicalcium silicate and a littleless than the one to one ratio to form mono-cat cium silicate.

5. Fertilizer materials in pulverulent form comprising artificialcalcium silicate other than mono-calcium silicate wherein the ratio ofcalcium oxide to silica varies between a little less than the ratiorequired to form di-calcium silicate and a little less than the one toone ratio to form mono-calcium silicate, and containing impurities suchas commonly occur in limestone and silica.

6. Fertilizer materials in pulverulent form comprising artificialcalcium silicate wherein the ratio of calcium oxide to silica variesbetween a little less than the ratio required to form di-calciumsilicate and a little less than the one to one ratio to form monocalciumsilicate, and containing alkali metal oxides and alumina as impurities.

7. Fertilizer materials in pulverulent form comprising artificialcalcium silicate wherein the ratio of calcium oxide to silica variesbetween a little less than the ratio required to form di-calciumsilicate and a little less than the one to one ratio to form monocalciumsilicate, and containing potassium metal oxides and alumina asimpurities.

8. The rocess of fertilization, which comprises sub ecting the soil to afertilizer comprising artificial calcium silicate other thanmono-calcium silicate, the artificial silicate between a little lessthan the ratio required containing the ratio of calcium oxide to silicavarying between a little less than the ratio required to form di-calciumsilicate and a little less than the one to one ratio to formmono-calcium silicate.

9. A fertilizer material comprising artificially prepared calciumsilicate other than mono-calcium silicate wherein the ratio of calciumoxide to silica varies between'a little less than the ratio required toform di-calcium silicate and seven-tenths to one.

10. A fertilizer material in pulverulent 'form comprising artificiallyprepared calcium silicate other than mono-calcium silicate wherein theratio of calcium oxide to silica varies between a little less than theratio required to form di-calcium silicate and seven-tenths to one. 7 I

11. A fertilizer material comprising artificially prepared calciumsilicate other than mono-calcium silicate wherein the ratio of calciumoxide to silica varies between a little less than the ratio required toform di-calcium silicate and seven-tenths to one and containingimpurities such as commonly occur in limestone and silica.

12. A fertilizer material comprising artificially prepared calciumsilicate having the molecular ratio of about seven-tenths molecules ofcalcium oxide to one of silica.

13. A fertilizer material composed. of artificially prepared calciumsilicate having the molecular ratio of seven-tenths molecules of calciumoxide to one of silica.

In testimony whereof I hereto aiiix my signature.

ALFRED H. COWLES.

